Formula for determining the heat dissipation of a radiator

In summary, the water cooled radiator with a fan on it can dissipate the 500 watt heat source effectively. The model used to calculate the heat dissipation is Newtonian cooling, which is a good model. The fan does not play a significant role in the rate of heat transfer. The only complication is that the data needed to design a radiator like this is hard to find.
  • #1
Daringpear
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0
Are there any equations out there which can calculate the heat dissipation of a water-cooled radiator with a fan on it? I would assume some of the variables would include:
-Volume of the radiator (240 x 199 x 45mm)=2149200mm^3
-Specific heat of water (4.187 kJ/kgK)
-Specific heat of the copper radiator fins (0.385 kJ/kgK)
-ΔT between the temperature of the coolant (variable we are solving for), and the ambient air temperature (lets assume 20 degrees C)
-Rate at which air moves over the radiator fins (3.115 cubic meters/minute)
-Rate at which water moves through the fins (3.785 Liters/minute)
-Energy being dumped into the system (500 watt heat source)

Ultimately what I want to accomplish, is find out if said radiator can adequately radiate 500W of heat (ΔT of less than 40 degrees C) in an ideal environment. Is there some equation into which I can plug these variables? Did I leave anything out?
 
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  • #2
Welcome to PF;
The short answer is "yes".

Forced convection: a good model would be "Newtonian cooling" carrying off heat on the outside. The rate of heat transfer is directly proportional to the temperature difference. The trick is determining the constant of proportionality ... which you can do experimentally, or there may be tables you can look up.
ie. http://www.engineeringtoolbox.com/convective-heat-transfer-d_430.html

The water flow is more about keeping the radiator surface at a constant temperature by moving heat from some source to the inside of the heater. So long as the flow can deliver heat at the same rate it is being dissipated you are fine.
You will be more interested in stead-state situation ... the situation as the heater warms up will be much more difficult to model and not tell you much.
For strong convection, there is a point where increasing the fan speed makes no difference to the rate of heat transfer ... which is what your description sounds like. What the fan does is blow away the warmer air close to the radiator... ie maintaining the temperature difference.
 
  • #3

FAQ: Formula for determining the heat dissipation of a radiator

1. What is the formula for determining the heat dissipation of a radiator?

The formula for determining the heat dissipation of a radiator is: Heat dissipation = (Temperature difference between radiator and environment) x Surface area of radiator x Heat transfer coefficient.

2. How do I calculate the temperature difference between the radiator and environment?

To calculate the temperature difference, you need to measure the temperature of the radiator and the temperature of the surrounding environment. Then, subtract the temperature of the environment from the temperature of the radiator.

3. What is the surface area of the radiator?

The surface area of the radiator can be calculated by multiplying the length, width, and height of the radiator. Make sure to use the same units for each measurement.

4. How can I determine the heat transfer coefficient?

The heat transfer coefficient can vary depending on factors such as the material of the radiator, the fluid being used, and the flow rate. It is best to consult a reference table or use a heat transfer calculator to determine the appropriate coefficient for your specific radiator.

5. Can this formula be used for all types of radiators?

While the formula can be used for many types of radiators, it is important to note that it may not be accurate for all types. Some radiators may require more complex calculations, such as those with fins or convoluted shapes. It is best to consult a heat transfer specialist for more accurate calculations for specific radiator designs.

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